<?php
//ucfirst(string $string): string
//ucfirst — 将字符串的首字母转换为大写

$foo = 'helloWorld';
$foo = ucfirst($foo);
echo $foo;
echo PHP_EOL;

$foo = 'hELLOWORLD';
$foo = ucfirst($foo);
echo $foo;
echo PHP_EOL;
